Sn对铜合金激光选区熔化微熔池组织及性能的影响

优化激光选区熔化(SLM)功率、扫速、扫描间距参数调控策略,使Cu-5%Sn、Cu-15%Sn和Cu-24.6%Sn(质量分数)合金成形致密度分别达99.2%、99.7%和99.7%。发现该SLM成形凝固相转变行为与显微组织均有非平衡凝固特征,α相Cu-5%Sn合金中主要为α-Cu(Sn)固溶体相,α相Cu-15%Sn合金中为α-Cu(Sn)与δ-Cu_(41)Sn_(11)两相,β相Cu-24.6%Sn合金中β相不完全分解而析出γ与δ相。Sn含量由5%增至15%,抗拉强度由384 MPa增至695 MPa,但断裂总延伸率由22.7%降至12%,α相中未见明显择优取向,β相Cu-24.6%Sn合金中有织构与SLM堆积方向平行,拉伸性能呈现强各向异性。     

选择性激光熔化成形CoCrWMo合金工艺优化及摩擦磨损性能

对选择性激光熔化成形CoCrWMo合金的工艺参数进行优化,并对最佳工艺下合金试样的摩擦磨损性能进行分析。结果表明:选择性激光熔化最佳工艺参数为激光功率280 W,扫描速度800 mm?s?1,铺粉层厚0.03 mm,扫描间距0.10 mm,扫描策略为旋转扫描法（层与层之间旋转15°）。该工艺下激光体能量密度为117 J?mm?3,试样相对密度为99.4%,上表面粗糙度（Ra）为4.98 μm,显微硬度为HV 386,抗拉强度为984 MPa,屈服强度为663 MPa,断后伸长率为12.9%。在干摩擦下,CoCrWMo合金的平均摩擦系数随施加载荷的增加呈下降趋势;受磨损过程中应变诱导马氏体转变的影响,合金平均磨损率呈现先增高后降低的变化规律,主要磨损机制为磨粒磨损和粘着磨损。     

选区激光熔化成形工艺参数对Fe20Cr5Al合金致密度和力学性能的影响

采用选区激光熔化(selective laser melting, SLM)成形技术进行3D打印,制备用于汽车尾气净化器载体的Fe20Cr5Al合金材料,采用响应曲面实验设计,系统研究打印参数(激光功率、扫描速度和扫描间距)与打印件致密度的关系,获得SLM成形参数与致密度的关系模型以及成形参数与力学性能的关系模型,并获得最佳的SLM成形工艺参数。结果表明,SLM工艺参数对打印件致密度的影响程度按从大到小依次为激光功率、扫描速度、扫描间距;最佳的SLM成形工艺参数为:激光功率314.8 W、扫描速度1 700 mm/s、扫描间距0.06 mm,在此工艺参数下相对密度的预测值为99.74%,这与SLM成形实验结果的平均误差仅为0.16%,模型具有较高的可靠性,在优化工艺参数下的平均实际相对密度达到99.58%,抗拉强度为616.44 MPa,伸长率为1.513%。     

选区激光熔化Al-Zn-Mg-Sc合金组织与性能研究

采用选区激光熔化(SLM)技术成形Al-Zn-Mg-Sc合金。研究了激光打印参数及热处理工艺对Al-Zn-Mg-Sc合金显微组织与力学性能的影响。研究结果表明, 打印态Al-Zn-Mg-Sc合金组织具有显著的各向异性特征: 建造面熔池为鱼鳞状, 晶粒为大尺寸柱状晶; 扫描面熔池则为条带状, 晶粒为小尺寸柱状晶与等轴晶。SLM成形的Al-Zn-Mg-Sc合金存在大量热裂纹, 严重影响合金力学性能。但热处理后, Al-Zn-Mg-Sc合金力学性能显著提高。经过热处理后合金的维氏(HV)硬度由91.70提升至144.27, 抗拉强度由183.71 MPa提升至257.53 MPa。      

选区激光熔化工艺对NiTi形状记忆合金相变及拉伸性能影响

采用选区激光熔化成形工艺制备了NiTi形状记忆合金,研究了不同工艺参数组合下激光能量密度对NiTi合金相变、显微组织、拉伸性能和形状记忆性能的影响。结果表明:激光能量密度在45～85 J?mm?3时,试样相对密度均在99.5%以上。随激光能量密度增大,试样中NiTi（B2）相含量有所减少,相变温度逐渐提高。在打印试样中均存在纳米Ti₂Ni相,随激光能量密度增大,析出相从均匀点状分布变为半网状分布。激光能量密度为47.62 J?mm?3的试样具有最优综合性能,样品的抗拉强度为(783±3) MPa,断后伸长率为(13.9±0.2)%,室温循环拉伸20次经热回复后回复率可达100%,可回复应变为2.75%。     

激光选区熔化GH3536镍基高温合金组织与性能研究

研究了激光选区熔化（SLM）GH3536合金扫描面与建造面的组织与性能。采用光学显微镜（OM）、 X射线衍射仪（XRD）、扫描电镜（SEM）和电子背散射衍射（EBSD）对激光选区熔化GH3536合金金相、物相、微观组织和晶粒特征进行研究。结果表明，通过优化成形参数可以减少合金中孔隙与微裂纹，但是无法消除。半椭圆形熔池广泛分布于建造面，其宽深比约为1.5。激光选区熔化GH3536合金由单一的面心立方γ奥氏体组成。扫描面与建造面都分布着大量胞状与柱状亚晶，建造面熔池交界处存在沿建造方向的微裂纹。建造面的平均晶粒尺寸（145.1μm）约为扫描面晶粒尺寸的4.5倍，织构强度约为扫描面的2倍。横向与纵向试样的拉伸性能存在明显差异，横向试样的屈服强度和极限抗拉强度分别为645 MPa和781 MPa，分别比纵向试样高4.1%和7.0%。激光选区熔化GH3536合金断口呈明显韧性断裂，存在大量韧窝。本研究有望为激光选区熔化GH3536合金扫描面与建造面组织与性能差异提供有效的参考。     

选区激光熔化ZL116组织与力学性能研究

ZL116合金广泛应用于航空航天领域高强度、高耐蚀性复杂零件的制备，伴随着装备向着整体化和多功能化发展，传统铸造等工艺难以满足该类零件的制备需求，以选区激光熔化成形技术(SLM)为代表的增材制造工艺基于离散-堆积的成形原理，在复杂零件的制备上具有显著的优势，目前关于SLM成形ZL116合金组织性能的研究较少。实验开展了SLM成形ZL116组织与力学性能研究，为SLM成形ZL116复杂零件提供理论支撑。采用SLM成形了ZL116试样，通过OM、SEM等表征手段分析了成形试样组织形貌，测试了成形试样的室温拉伸性能和疲劳性能。结果表明（：1）SLM成形ZL116铝合金组织为底部向顶部外延生长的柱状晶，晶界上弥散分布细小硅颗粒（；2）合金力学性能存在各向异性，平行于成形方向拉伸性能较差（；3）合金的抗拉强度可达340 MPa，伸长率超过10%，硬度达110 HB，疲劳极限强度为185 MPa。     

选区激光熔化铝合金制备研究现状

选区激光熔化（selective laser melting,SLM）技术因具有可定制化、加工周期短及精度高等特点,在工业生产中得到广泛应用。本文对选区激光熔化技术及其在铝合金及铝基复合材料制备的研究现状进行了综合性论述。通过论述选区激光熔化特性引出选区激光熔化打印铝合金的优势。介绍了适用于选区激光熔化技术的铸造Al?Si系合金,结合扫描策略和工艺参数优化,探究了选区激光熔化铝硅合金的微观结构、相组成和力学性能变化规律。讨论了选区激光熔化微/纳米陶瓷强化铝基复合材料的研究现状,分析与总结了添加强化颗粒对组织结构、相对密度、润湿性及相应力学性能的强化机理。总结了工业界与学术界关注的新型高强度铝合金材料的开发及其选区激光熔化的制备,重点论述了新型铝合金的固溶强化和析出相强化机理,并分析了对相对密度和力学性能的影响因素。最后对选区激光熔化铝合金发展趋势及现阶段存在的问题进行了展望。     

LDM连接及SLM成形TC4合金的组织与性能

以TC4粉末为原料,采用激光沉积制造技术,对选择性激光熔融成形件进行连接,可获具有复杂精细结构的大型整体构件。对连接成形件试样进行拉伸性能测试,利用光学显微镜（OM）及扫描电子显微镜（SEM）观察了各区域组织及断口形貌,研究连接件组织与性能的关系。结果表明：连接件组织差异明显,分为选择性激光熔融（selective laser melting,SLM）、热影响区（heat affected zone,HAZ）、激光沉积制造（laser deposition manufacturing,LDM）3个区域,SLM区由α片层组成,HAZ由分布更加杂乱的α片层组成,LDM区由长直的α′马氏体组成,3个区域显微硬度依次降低。连接件的强度和塑性低于SLM成形件,抗拉强度均达到1140 MPa以上,屈服强度达到1050 MPa以上,连接件的伸长率降低48.41%,断面收缩率降低35.14%,强度降低较小,塑性降低较明显。连接件的断裂位置发生在LDM区,断裂机制为半解理半韧性断裂。就两种不同沉积方向的连接方式而言,LDM与SLM沉积方向垂直的连接方式,其强度和塑性均高于LDM与SLM沉积方向平行的连接...     

机械合金化法制备(Ag-Cu28)-xSn合金的结构和性能研究

利用机械合金化法制备(Ag-Cu28)-xSn系合金粉末,借助差示扫描量热仪、X-射线衍射仪、扫描电镜等,研究了Sn含量对合金熔化温度、球磨时间对合金粉末的物相组成及显微结构的影响。研究表明:Sn对合金的熔化温度有显著影响,随Sn含量增加合金熔化温度下降趋势减缓;当Sn含量为30%时,合金熔化温度最低为539.3℃。球磨40 h时,(Ag-Cu28)-30Sn粉料合金化完全,其物相组成为Ag4Sn、Cu3Sn和Cu6Sn5。球磨初始阶段(Ag-Cu28)-30Sn粉料颗粒异常长大,球磨至40 h时合金化完成,颗粒断裂和焊合达到平衡,合金粉末粒度均匀,平均粒径约为5~10μm。     

Development and characterisation of direct laser sintering multicomponent Cu based metal powder

Abstract

Recent advances in direct metal laser sintering (DMLS) have improved this technique considerably; however, it still remains limited in terms of material versatility and controllability of laser processing. In the present work, a multicomponent Cu based metal powder, which consisted of a mixture of Cu, Cu–10Sn and Cu–8·4P powder, was developed for DMLS. Sound sintering activities and high densification response were obtained by optimising the powder characteristics and manipulating the processing conditions. Investigations on the microstructural evolution in the laser sintered powder show that liquid phase sintering with partial or complete melting of the binder (Cu–10Sn), but non-melting of the cores of structural metal (Cu) acts as the feasible mechanism of particle bonding. The additive phosphorus acts as a fluxing agent to protect the Cu particles from oxidation and shows a concentration along grain boundaries owing to the low solubility of P in Cu and the short thermal cycle of laser sintering. A directionally solidified microstructure consisting of significantly refined grains is formed, which may be ascribed to laser induced non-equilibrium effects such as high temperature gradient and rapid solidification.     

Al?Zn?Mg?Cu?Zr?(Sc)合金搅拌摩擦焊接头组织和性能

利用光学显微镜、透射电子显微镜、显微硬度计和万能拉伸试验机等分析手段,表征了Al?Zn?Mg?Cu?Zr?(Sc)合金搅拌摩擦焊（FSW）接头的显微组织和性能,探究了Sc元素对改善超高强Al?Zn?Mg?Cu?Zr合金焊接性能的作用机制。结果表明:Al?Zn?Mg?Cu?Zr?(Sc)合金焊接接头具有相似的组织特征,焊核区为动态再结晶组织,由细小均匀的等轴晶组成,包含较高密度的位错线,大部分时效析出相回溶;热力影响区晶粒被拉长,位错密度更高,残留的时效析出相显著粗化;热影响区保留与母材相同的晶粒形态,大部分时效析出的η'相发生长大,少部分粗化成η相。添加质量分数0.17%的Sc,可以使合金FSW接头抗拉强度提升43 MPa,屈服强度提升23 MPa,断后伸长率改善2.3%,焊接系数达到74.1%。Al₃(Sc,Zr)二次析出相可以强烈抑制位错、亚晶界、晶界的移动,细化晶粒的同时保留大量的亚结构,且自身可发挥Orowan弥散强化作用。因此,可通过细晶强化、亚结构强化和弥散强化三种方式显著提高合金FSW接头的力学性能。      

High temperature properties of Cu–Cr–Zr alloys processed by conventional inverse extrusion of atomised powders and comparison with Conform consolidated powders

Abstract

Water atomised Cu–Cr–Zr alloy powders were consolidated by inverse warm extrusion and by the commercial continuous rotary extrusion method, Conform. Those alloys consolidated by inverse warm extrusion exhibited enhanced mechanical properties compared with their respective Conform extruded counterparts, when tested at both room and elevated temperatures. The processing parameters adopted in the inverse extrusion experiments resulted in products which retained enough amounts of solutes in solid solution, which in turn, led to improved mechanical properties after aging. Conversely, the excessive adiabatic heat generated in the Conform machine eliminated the saturation effect produced by rapid solidification, negating any possible further improvement on the mechanical properties by aging. The mechanical properties of an inverse extruded Cu–2.8Cr–0.39Zr (at.-%) alloy at temperatures above 450°C were higher than those strengths reported for Cu–Be alloys and comparable to that of Cu–Ta and Cu–Nb composites. Therefore, rapidly solidified Cu–Cr–Zr alloys can be possible candidates for replacing such alloy systems for high temperature applications.     

Solidification Microstructure and Mechanical Properties of Cast Magnesium-Aluminum-Tin Alloys

The solidification microstructure and mechanical properties of as-cast Mg-Al-Sn alloys have been investigated using computational thermodynamics and experiments. The as-cast microstructure of Mg-Al-Sn alloys consists of α-Mg, Mg₁₇Al₁₂, and Mg₂Sn phases. The amount of Mg₁₇Al₁₂ and Mg₂Sn phases formed increases with increasing Al and Sn content and shows good agreement between the experimental results and the Scheil solidification calculations. Generally, the yield strength of as-cast alloys increases with Al and Sn content, whereas the ductility decreases. This study has confirmed an early development of Mg-7Al-2Sn alloy for structural applications and has led to a promising new Mg-7Al-5Sn alloy with significantly improved strength and ductility comparable with commercial AZ91 alloy.     

Study on Improving Solidification Structure of Rare Earth Al-Si Alloys with Electropulse Acting on Liquid Alloy

Electropulse modification (EPM) process, a new physical field method for improving the solidification structure of metals was introduced.Different from other research, EPM is only acting pulse current on melt under liquid state.The solidification structure of Al-Si alloys, A1-Cu alloys,cast iron and steel can be modified obviously with this method: the solidification structure of ZL101 alloy presented the Na and Sr modification and the mechanical properties were enhanced; a large number of primary silicon appeared in the microstructure of ZL109 alloy; the equiaxed grain zone was expanded and the grains were fined in Al-5.0wt% Cu alloy; the graphitization took place in solidification process of molten cast iron; the grain sizes of solidification structure of T8 steel were reduced significantly and the shape of steel pearlites also changed; the equiaxed grain zone increased to 88% from original untreated 19%, the equiaxed grains were fined and the intercrystalline crack was avoided in concasting billet by continuously treating liquid electrical sheet steel in tundish.Effects of rare earths on casting Al-Si alloys were also summarized.The method of modifying the solidification structure of rare earth Al-Si alloys with EPM in producing the alloys was proposed.     

Influence of Strontium Addition on Microstructure and Mechanical Properties of an Al–10Si–5Cu Alloy

The microstructure and mechanical properties of Al–10Si–5Cu cast alloys with micro-addition of alloying elements (V, Cr and Ni) were studied before and after strontium addition. Samples were examined using the X-Ray diffraction, the optical microscope, the scanning electron microscope and the energy dispersive spectrometer. The results indicated that the α-Al matrix, eutectic Si phase and Al₂Cu phase were the main constituent phases of Al–10Si–5Cu alloys before or after strontium addition. Strontium addition affected the refining of the α-Al grains and transforming the configuration of interdendritic phases. The un-modified alloy showed a brittle nature because of existing brittle and aggregated AlSiMnFe phases. Contributing to the alteration of microstructure in strontium modified alloy, the strength and elongation of the alloy were improved. In addition, the fracture mechanism and crack propagation process were investigated in both the alloys.     

SLM成形Al-Cu-Mg 合金的摩擦磨损性能

铝合金具有低密度、高比强度、较好的耐蚀性等优点，被广泛应用于航空、船舶和汽车等领域；选区激 光熔化成形可以一次性成形复杂零件，具有良好的应用前景。对选区激光熔化（SLM）成形的Al-Cu-Mg 合金 摩擦磨损性能进行了研究，并与成分相近的铸造ZL205A合金性能进行对比，结果表明，采用SLM工艺成形可 细化合金晶粒，改变Al2Cu 的尺寸与分布，使晶粒细小均匀。与铸造ZL205A合金相比，SLM成形Al-Cu-Mg 合金的磨损率和摩擦因数均有不同幅度的降低。SLM成形Al-Cu-Mg 合金横截面的耐磨性最好，纵截面耐磨 性次之，铸造ZL205A的耐磨性最差。SLM成形Al-Cu-Mg 合金的磨损机制随着载荷的变化而不同：低载荷时 的磨损机制以磨粒磨损为主，粘着磨损和塑性挤出磨损并存；中载荷时的磨损机制为磨粒磨损、粘着磨损并伴 随氧化磨损；高载荷时的磨损机制主要为剥层磨损、粘着磨损和氧化磨损的综合作用。     

Microstructures and strengthening mechanisms of Mg-8.2Gd-4.6Y-1.5Zn-0.4Zr alloy containing LPSO,β' and γ type phases

The microstructures and strengthening mechanisms of the Mg-8.2 Gd-4.6 Y-1.5 Zn-0.4 Zr(wt%) alloy with long-period stacking ordered(LPSO),β' and γ type phases were systematically studied.The results show that the LPSO with lamellar and block structures forms near the grain boundaries.The grains are clearly refined,and the 18 R LPSO phase is oriented along the extrusion direction after extrusion.Some particles also precipitate from the Mg matrix dynamically.The extruded alloy exhibits a remarkable agehardening response,and mechanical properties,with a tensile strength(TS) of 449 MPa,yield strength(YS) of 362 MPa,and elongation of 7.9% obtained in the peak-aged alloy.The strengthening mechanisms of the alloy in different states are discussed.Grain boundary and precipitation strengthening are the main strengthening mechanisms for the peak-aged alloy.     

Sn含量对Cu基金刚石锯片胎体组织与硬度的影响

以Cu为基体,加入Co,Fe,Cr,Sn粉末,改变Sn含量,经过模压成形与热压,制备Cu基金刚石超薄切锯胎体材料,用显微硬度仪、金相显微镜(OM)、扫描电镜(SEM)和X线衍射(XRD)表征该胎体材料的显微硬度、组织和成分,研究Sn含量对胎体组织和硬度的影响。结果表明:采用烧结温度700℃、烧结压力8.2 MPa的工艺烧结出的胎体中,当Sn的质量分数为2%时,烧结Cu基锯片胎体平均硬度(HV0.1)最低为885.82 MPa;当Sn含量为12%时,烧结Cu基锯片胎体平均硬度最高为1 914.72 MPa。胎体中Sn含量从2%增加到6%,由于胎体中铜锡固溶体的含量增加,Cu基锯片胎体的平均硬度增加,胎体中Sn含量从8%增加到12%时,胎体中铜锡固溶体的含量减少,但是铜锡中间相含量增加,Cu基锯片胎体的平均硬度增加并达到最大值;胎体中Sn含量高于8%时,液态Sn会从胎体中流出,锯片与模具粘着严重,严重影响锯片成形率。